I've just got my own MBP 13" after having a school loaner for a couple of months. When I used the school loaner the battery capacity decreased to 95% in the course of 4 months. I don't want the same thing to happen to my new MBP. I don't have a real need of using the battery except 2 times a week (when I go teach). So, I can plug it in 99% of the times that I use it. What's the best way to conserve the battery capacity? Should I use it plugged in most of the time?